Nausea and Vomiting in Pregnancy

By
Hannah Dahlen

Nausea and vomiting affect 50-90% of pregnancies (1). Beginning from before 9 weeks gestation it most commonly resolves between 10 and 16 weeks gestation (2). Although referred to as 'morning sickness' the nausea and vomiting in pregnancy may occur throughout the day.

Nausea and vomiting in pregnancy is thought to be associated with raised thyroxine levels and Human Chorionic Gonadotropin (HCG) or suppressed Thyroid Stimulating Hormone (TSH) levels. There is no good evidence to support psychological and behavioural theories (1). It is important that other causes of nausea and vomiting be ruled out. Idiopathic nausea and vomiting in pregnancy must be distinguished from nausea and vomiting in pregnancy of known causes such as hydatiform mole or multiple gestation.

The physical and emotional impact of nausea and vomiting in pregnancy often results in feelings of anxiety about the effect of the symptoms on the baby. Nausea and vomiting in pregnancy also impacts on a woman’s family relationships and ability to work. Around 47% of working women with nausea and vomiting in pregnancy feel their job efficiency is reduced (3). Around 35% lose work time and 25% lose time from housework. Nausea and vomiting in pregnancy has also been cited as a reason for elective termination of pregnancy (4). This is not surprising when you consider studies that have found nausea and vomiting in pregnancy experienced by pregnant women is comparable to that experienced by patients undergoing chemotherapy for cancer (5).

Management of mild nausea and vomiting

Women should be reassured that nausea and vomiting in pregnancy is normal, and in mild to moderate cases it is not associated with adverse outcomes. Nausea and vomiting in pregnancy is associated with a decreased risk of spontaneous abortion (1,6). There are dietary changes and alternative therapies that can help in the management of nausea and vomiting in pregnancy.

Further reading

Dr Hannah Dahlen is the Associate Professor of Midwifery at the University of Western Sydney. She has been a midwife for more than 20 years. Hannah is also an executive member of the Australian College of Midwives, NSW Branch. She has researched women's birth experiences at home and in hospital and published extensively in this area. Hannah's website is www.hannahdahlen.com.au